High tuberculosis transmission rate in children with nursery exposure to undetected pulmonary tuberculosis

SETTING

Nursery for newborns in Busan, Republic of Korea.

OBJECTIVE

To evaluate tuberculosis (TB) transmission from a health care worker with active pulmonary TB to neonatal contacts.

DESIGN

For the first investigation, infants who had been in the nursery 3 months before the index patient was diagnosed with pulmonary TB were enrolled. After a child who had stayed in the nursery 10 months before the diagnosis of the index patient was diagnosed with tuberculous meningitis, a second contact investigation was conducted.

RESULTS

Respectively 315 and 1334 children participated in the first and second investigations. The mean age of the contacts was 66.3 days; the rate of latent tuberculous infection (LTBI) at the first investigation was 42.5% (134/315). Only one infant had an abnormal chest X-ray, and was thought to have pulmonary TB. In the second investigation, the mean age of the participants was 17.6 months. The proportion of children with LTBI was 18.7% (249/1334).

CONCLUSIONS

The LTBI rate in the present study was much higher than that estimated from other contact investigations. To minimise the risk of nosocomial TB transmission to neonates, screening and management of TB in health care workers should be strengthened.

Optimal matchline blocking and matchline dosimetry for lymphoma patients

Patient setup and geometrical factors can potentially lead to excessive spinal cord doses when treating lymphoma patients with matched mantle and para-aortic (PAN) fields. To ensure cord protection, partial transmission blocks are often used at the matchline. This study evaluates optimal placement of these blocks. Three patients were planned using a variety of mantle/PAN field geometries, including significantly different field lengths and isocenter vertical positions. Field matching in all cases was based on a standard gap calculation. Half-transmission blocks (HTB) were positioned on (a) both posterior fields, (b) both anterior fields, and (c) the posterior PAN field only. Doses were calculated with and without effects of setup uncertainty. HTB on both posterior fields yielded a lower maximum cord dose but slightly poorer target coverage than HTB on both anterior fields. HTB on the posterior PAN field alone resulted in a maximum cord dose similar to HTB on both anterior fields. Setup uncertainty decreased but did not eliminate the differences between block placement methods. HTB of sufficient size on both posterior fields ensures a maximum cord dose less than the prescription without significant compromise of target coverage.

Comparison of 2D conventional, 3D conformal, and intensity-modulated treatment planning techniques for patients with prostate cancer with regard to target-dose homogeneity and dose to critical, uninvolved structures

The purpose of this study was to compare 2-dimensional (2D), 3-dimensional (3D) and intensity-modulated radiation therapy (IMRT) techniques for external-beam radiation treatment for prostate cancer. Dose homogeneity within the target volume and doses to critical, uninvolved anatomic structures were evaluated. Computed tomography (CT) scans of 3 patients with localized prostate cancer (T2NOM0) were acquired and transferred to the treatment planning systems. The target volume and uninvolved structures were contoured on axial CT slices throughout the volume of interest. A comparison of the 3 treatment techniques was performed using isodose distributions, dose statistics, and dose-volume histograms. Dose homogeneity was found to be most uniform with the 2D technique; however, the 2D technique delivers unnecessary radiation doses to the rectum and bladder. The dose conformity observed with IMRT is increased compared with that observed with the 3D technique, as is the sparing of critical uninvolved structures; however, dose homogeneity appears to be worse with IMRT than with the 3D technique. Overall, of the 3 techniques, IMRT offers the most conformity in delivery of tumoricidal doses to the prostate while sparing dose to critical, uninvolved structures. Association of Medical Dosimetrists.

bendless, a Drosophila gene affecting neuronal connectivity, encodes a ubiquitin-conjugating enzyme homolog

The Drosophila bendless (ben) gene was originally isolated as a mutation affecting the escape jump response. This behavioral defect was ascribed to a single lesion affecting the connectivity between the giant fiber and the tergotrochanter motor neuron. A closer examination of the ben phenotype suggests that ben activity is broader and affects a variety of other neurons including photoreceptor cells and their axons. Mosaic analysis indicates that the focus of ben activity is presynaptic. We have cloned the ben gene through a chromosomal walk and show that it is homologous to a class of ubiquitin-conjugating enzymes. The major role of ubiquitination in the protein degradative pathway suggests that ben regulates neural developmental processes such as growth cone guidance by targeting specific proteins for degradation.

Isolation of cDNAs encoding the Drosophila GAGA transcription factor

To investigate the mechanisms involved in expression of the Drosophila melanogaster engrailed gene, we purified GAGA protein, one of several putative transcriptional activator proteins that binds to the proximal region of the engrailed promoter. Antibodies raised against GAGA protein were used to demonstrate that the protein is present in all nuclei of young embryos. We isolated cDNA clones encoding GAGA protein in which a putative 519-codon open reading frame contains general sequence motifs characteristic of other transcription factors. These include stretches of polyglutamine, a 60-amino-acid region with 18 (30%) lysine or arginine residues, and a single putative zinc finger motif. In addition, a 120-residue N-terminal region shares significant sequence homology with several other known Drosophila transcription factors, including those encoded by Broad Complex and tramtrack. Up to 35-fold GAGA protein-dependent stimulation of transcription in Schneider line 2 tissue culture cells was observed after transfection of GAGA protein-encoding sequences. The GAGA gene is present in one copy in the Drosophila genome, at cytological location 70EF, and it encodes RNAs which vary in size between 2.4 and 4.4 kb.